Tumour necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) has been implicated in the pathogenesis of a variety of inflammatory disorders and autoimmune diseases. However, studies conducted on the relationship of TWEAK and psoriasis patients are limited. In this study, we aimed to explore the serum levels of TWEAK and detect the association betwen TWEAK levels associated and clinical variables .The severity of psoriasis was assessed by the Psoriasis Area and Severity Index (PASI). This study aims to evaluate the serum levels of TWEAK in severe psoriasis vulgaris patients. this study included 52 individuals, 28 males and 24 females, allocated from dermatology outpatient clinic at Benha University hospital. Participants were divided into patients group and a control group of normal individuals. All participants were subjected to complete history taking, clinical examination and laboratory assessment of TWEAK levels. The study group included 22 severe psoriasis patients, their ages ranged from 27.5 to 42.5 years old. Control group included 30 individuals, their ages ranged from 25 to 49 years old. PASI score for psoriasis cases ranged from 16-38. TWEAK levels were 5.6±1.3 (ng/mL) and 4.7±0.7(ng/mL) for control group and cases group respectively without any statistical significance (p>0.05). TWEAK levels are insignificantly decreased in patients with severe psoriasis vulgaris.